1. Field of the Invention.
The invention relates to grinding machines and more particularly to grinding heads of such machines.
2. Description of the Prior Art.
Grinding machines are known which permit obtaining gauged bores with very small tolerances. However, if it is desired to eliminate inlet and outlet defects in a very precise manner, it is necessary to insert and remove the grinder in a contracted state, which requires an automatic expansion control. This control must be both fast and very accurate because it should be able to impart to the grinder the diameter it had during the previous operating stroke, with an accuracy of less than one tenth of a micron. Automatic grinders at present in existence do not permit making recessed bores with tolerances of less than one micron.